it oscilate at 900hz square,, now i want to divide the freq into 90 Hz and 150 hz,. i 've had the divider cct with jk flip-flop n dflip-flop. one i dont understand is how to adjust the level ofXR2206 to digital circuit...i use 74ls76 jk for divider,, help please

I would double check the 4017 to give variable divisions without external gating. It is a basic divide by 10 counter with 10 decoded outputs. Any single output will simply divided the input frequency by 10.

Are you limited to using the ls76 jk flip flops for the dividers? You will need a divide by 10 for the first result and a divide by 6 for the second. These are implemented in the ls90 counter and ls92 counter ICs respectively. Otherwise, you will have to construct your own. Similar results can be obtained by using two 4017 ICs.
(BTW, this is a duplicate post RE: confused)